... 30-45100-200 15-40Below 200 15-30PropertyAsh, max % wtCarbon residue, max % wt Distillation, 90% point, max °F Distillation, 90% point, min °FFlash point, min °FGravity, API minGravity, ... 1967.5. Kempe's, Engineering Yearbook, Morgan Grompium, London.6. W. L. Nelson, Petroleum Refinery Engineering, McGraw-Hill, New York, 1968.7a. E. M. Shelton, Diesel Oils, ... six carbons),Very little crude petroleum is used in its natural state. Refining is required to yield marketableproducts that are separated by distillation into fractions including...